1. Field of the Invention
This invention relates to the control and configuration of a compound printer whereon two or more printing mechanisms are mounted.
2. Background of the Invention
When the cover of a printer is opened during printing to change or add printing paper, subsequent printing processing cannot be assured. Because of this, a personal computer or other host device is notified of the printer status by sending a busy signal indicating that the processing of data being transferred cannot be assured. Specifically, many printers indicate this busy state by making the data terminal ready (DTR) signal inactive. The printer also executes error processing that interrupts printing after completing printing of the line in progress because it cannot be guaranteed that printing can be continued after the cover is opened.
Hybrid printers having two or more printing mechanisms as shown in FIG. 3 have been recently developed. A hybrid printer 1 will typically have non-impact type thermal printing mechanism 10 and impact type wire dot printing mechanism 20 as well as control circuit 30 with functions to control printing mechanisms 10 and 20 based on data transferred from a host device. Thermal printing mechanism 10 comprises thermal head 11, paper feed roller 13 for feeding thermal paper (roll paper) 12 to thermal head 11, and paper feed motor 14 and speed reducing gear 15 for driving paper feed roller 13. Wire dot printing mechanism 20 comprises print head (wire dot head) 24 disposed opposite platen 21 with ribbon 22 between them and moved left and right by carriage 23 driven by a motor not shown in the figure, paper feed roller 26 for feeding slip form 25 to the print head 24, and slip form feed motor 27 and gear set for driving paper feed roller 26.
In this type of hybrid printer 1, customer receipts, for example, are printed on thermal paper 12, which is provided in rolls, using thermal printing mechanism 10, and slip forms 25 such as checks and vouchers are printed using wire dot printing mechanism 20. Two different types of documents can therefore be printed on one printer 1, thus making the printer useful for point-of-sale (POS) terminals. Variations in printing can be considered such as using thermal printing mechanism 10 for printing journals for preserving store sales records and using wire dot printing mechanism 20 to perform authentication printing, in which case four types of printing operations could be performed in one printer.
A hybrid printer having two such types of printing mechanisms requires that a new control method for error processing be developed. For example, it is desirable to perform one type of error processing when cover 19 of thermal printing mechanism 10 is opened to add paper and perform another type of error processing when cover 29 of wire dot printing mechanism 20 is opened to replace ribbon 24.
For example, since feeding of the paper in thermal printing mechanism 10 is performed by turning the platen, it is desirable to stop printing immediately when it is detected that the cover has been opened and the platen has moved away from the paper. However, since printing can be continued in wire dot printing mechanism 20 even if opening of the cover is detected, if for a short period, it is desirable to complete printing of the line being printed in order to preserve data.
Also, when the cover is closed following stopping printing due to opening of the cover, form feeding before starting printing cannot be performed in thermal printing mechanism 10 because roll paper is used. However, when slip forms are used in wire dot printing mechanism 20, it is desirable that printing be restarted by setting slip form 25 at the printing location after form feed processing.
If a busy signal is output when one of the printing mechanism covers is opened in a prior hybrid printer wherein two printing mechanisms are integrated, data can no longer be transferred from the host device to the hybrid printer even if the other printing mechanism is operable. Therefore, in order to effectively utilize a plurality of integrated printing mechanisms, it is desirable to output busy signals corresponding to the respective states of the integrated printing mechanisms.